linux-kernel - Re: [BUG] seltests/iommu: runaway ./iommufd consuming 99% CPU after a failed assert()

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Message-ID: <20240319135852.GA393211@nvidia.com>
Date: Tue, 19 Mar 2024 10:58:52 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Mirsad Todorovac <mirsad.todorovac@....unizg.hr>
Cc: iommu@...ts.linux.dev, Kevin Tian <kevin.tian@...el.com>,
	Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [BUG] seltests/iommu: runaway ./iommufd consuming 99% CPU after
 a failed assert()

On Tue, Mar 12, 2024 at 07:35:40AM +0100, Mirsad Todorovac wrote:
> Hi,
> 
> (This is verified on the second test box.)
> 
> In the most recent 6.8.0 release of torvalds tree kernel with selftest configs on,
> process ./iommufd appears to consume 99% of a CPU core for quote a while in an
> endless loop:

There is a "bug" in the ksefltest framework where if you call a
kselftest assertion from the setup/teardown it infinite loops

The fix I know is to replace kselftest assertions with normal assert()

But I don't see an obvious thing here saying you are hitting that..

Jason